Returning to the United States and based in Hollywood, he was cast in 2011 as Fandral in Thor after Irish actor Stuart Townsend withdrew from the role days before filming was to begin. As he was a virtually unknown actor when cast, there was some speculation that Dallas was selected because there simply was not enough time to find a bigger name replacement. To prepare for the role, Dallas viewed Errol Flynn as an inspiration (Stan Lee, in 1965, created the character based on Flynn), and watched many of his films. He commented, "I tried to bring out that little bit of Flynn-ness in it. Flynn had a lot of that boyish charm and Fandral's got all that in him. "